1. Field
Apparatuses and methods consistent with exemplary embodiments relate to a gas turbine system, and more particularly to, a gas turbine system that adjusts the Wobbe Index (WI) of a fuel mixture and operates with the adjusted fuel mixture.
2. Description of the Related Art
Performance of an apparatus for generating power using fuel is very important. Factors for determining such performance are diverse. In particular, the Wobbe Index (WI) among the factors for determining the performance may be used to size a fuel system. The WI is an index indicating size of heat input energy with respect to a combustor according to a fuel component and may be expressed as a function of a heating value and specific gravity. In particular, the WI is used as an indicator of the interchangeability of fuel gases in a fuel system and may have variations of up to 5%.
The WI may be defined as Equation 1 below,
                    WI        =                  LHV                                    (                              Sp                .                Gr                            )                                                          [                  Equation          ⁢                                          ⁢          1                ]            
wherein LHV denotes a lower heating value in Kcal/Nm3, and Sp.Gr denotes a specific gravity of gas at 0° C. and 1 atm.
The WI may be modified and the modified Wobbe Index (MWI) may be defined as Equation 2 below,
                    MWI        =                  LHV                                    (                              Sp                .                Tg                            )                                                          [                  Equation          ⁢                                          ⁢          2                ]            
wherein LHV denotes the lower heating value in Kcal/Nm3, and Sp.Tg denotes an absolute temperature of gas at 1 atm.
The WI or the MWI is an important issue in designing the fuel system as described above. For example, if a change in a value of the WI or the MWI is great, since the fuel system needs to be changed as a whole, the entire fuel system is newly designed or manufactured. Thus, if it is possible to control the WI according to the fuel component, an existing fuel system may be utilized without newly designing or manufacturing the entire fuel system.
Meanwhile, methods of controlling the WI or the MWI may be diverse. For example, as a prior art publication relating to controlling an amount of air supplied to a combustor, Japanese Patent Application Publication No. 1994-323166 discloses separately controlling a flux of fuel supplied to a fuel nozzle to obtain an optimal air-to-fuel ratio.